Production of half-stuff paper-pulp or paper.



WILLIAM.ARTHUR RANKEN MICHAEL MGRAE, LONDON, ENGLAND, ASSIGNOR OF ONE-HALF TO NORMAN MALCOLMSON, OF LONDON, ENGLAND.

PRODUCTION OF HALF-STUFF PAPER-PULP OR PAPER.

No Drawing.

To all *w/tom it may concern:

;Be it known that I, WILLIAM ARTHUR RANKEN MICHAEL MORAE, a subject of the King of England, residing at London, in -England, have invented certain new and useful Improvements in the Production of Half-Stuff Paper-Pulp or Paper, of which the following is a specification.

This invention relates to improvpments in the productionof paper and has particular reference to the production of papermakers half-stufi .or paper pulp from megass or other-like canes.

According to this invention a process for the treatment of megass or like canes for the production of the material referred-to above consists in treating previously crushed raw material by boiling or cooking it with a solution of water containing lime only, Washing the treated material and subsequently disintegrating the washed product.

All plant substances consist of a mixture of cellulose and non-cellulose compounds more or less cemented together, the latter serving as the binding complex, and theprlmary function of the chemical treatment is to separate these constituents in order that the cellulose may be rendered available for the manufacture of paper. Lime, known as an alkaline earth, serves admirably for this purpose, though like the alkalis caustic soda and potash i. e. hydrates of soda and potash, or the carbonates of these elements hydrolysis of the non-cellulose compounds takes place. In the case of the latter, the hydrolysis is much more drastic owing to their complete solubility in water over 50% for the hydrates and about 17% for the carbonates, whereas in the case of caustic lime, the solubility is only about 0.13%, and it is only when this amount in solution is neutralized by the acid (e. g. acetic acid) products formed as the result of hydrolysis, that a fresh quantity of the undissolved lime can pass into solution to again act upon the fiber substance and continue the action. It is thus clearly seen that by the lime process the resolving action is more restrained, and progressive, and consequently the degrading action is much less.

This is clearly illustrated by the relatively pale colored compoundsformed by the break-down of the non-cellulose compounds, when boiled with lime, as compared to the dark, in point of fact, almost black colored Specificationof Letters Patent. Patented. Aug. 2%, 1915.

Application filed March 25, 1912. Serial No. 686,125.

tion they should be crushed or broken up to render them more permeable to fluid, either liquid or gas. In this condition they are then boiled with live steam under pressure with milk of lime in digesters or boilers of a any well-known type commonly employed in the treatment of other substances for the production of paper pulp or the like. The time of boiling varies from 4l6 hours and depends, as will be readily understood, upon the pressure of the steam, the grade of material, the type of digester, quantity of lime, and the class or quality of the resultant paper to be produced. The pressure employed may vary between 40 lbs. and about 100 lbs. per square inch.

It is preferable to pass the lime in the form of milk of lime through a sieve which may conveniently be wire gauze, before running it into the digester. The quantity of lime used may vary preferably from 525% by weight of the-dry weight of the raw material before it is placed in the digester, although the actual quantity employed will vary in accordance with the features referred to above in connection with the time necessary for the boilingoperation.

After the cooking operation, the product is preferably allowed tomellow. The subsequent action of mellowing after the boiling operation is a very important one. As mentioned previously caustic lime is only very slightly soluble in water, and as is Well known, bacterial action is very active when soluble organic compounds containing traces of nitrogenous matter are on the slightly alkaline side. Such a condition of things where fermentative action is most pronounced, is easily obtained, because free lime, if present in such a proportion as to restrain fermentation, would combine with the carbonic acid in the atmosphere, to form -,action is a progressive one,

an inert compound, namely, chalk. Here again, when once fermentation sets in, the the non-cellulose compounds being first to respond to such treatment and forming lime salts by the combination of lime with the organic acids formed as a result of this action. These are removed by subsequent washing. Care must, of course, be used here because the cellulose itself can be attacked to form degraded products. If caustic, or carbonates of alkali were used, however, the excess of the alkali which would naturally be present in the liquor, would in most cases be quite sufficient to act as an inhibitor to the growth of bacteria, hence the fermentation action would be m'Z. The stock thus produced is nexttreatedin a potcher and washed therein with water, the circulation and motion of the contents of .the potcher. being maintained by a paddle-wheel disposed therein or by. a centrifugal stuff-pump or other means. This washing operation must be completed before further treatment of the material, as it is necessary to remove the pithy and mucilaginous substance originally forming the portion of the core of the cane.

"With regard to a paper containing pith, it

is quite true that a good paper can be made containing a small proportion of parenchyma tissue, of which the'pith is composed,

but the use of such a material would render the paper unworkable on the machine. Pith is not a true normal cellulose, but is a mixture of beta and gamma celluloses, and such celluloses have the property of hydrating, that is, combining with water to such an extent as to render the pulp mixture almost like mucilage. It is clear, therefore, that in the production of a paper in which for commercial purposes, rapid separation of water should take place, such a condition of things I would be impossible. Furthermore, megass contains a large proportion of silica. In the use of caustic alkali under pressure, this silica may form an alkali silicate, which addsto the brittleness of the product when dry and also increases its refractory qualities when in the kollergang making the mass viscous, foamy andsluggish. Lime will not unite with silica under conditions of the I present case and the silica is accordingly readily eliminated. The Washing operation also removes other matter and it is found that unless such impurities are removed before the step next to be described, they are retained permanently in the material and are found to be largely'detrimental to the production of a satisfactory stock.

After suflicient treatmentin the potcher the excess water is expressed, extracted or drained away in any suitable manner, The partially dried stock after the water has been removed is then transferred'to a kollergang or edge runner to be disintegrated.

The treatment in the kollergang may last approximately from %1 hour, according to the degree of disintegration required. The

resultant material is then in the form of papulp or paper.

If desired, the half-stuff produced from any of the materials may be used separately for the production ofpaper or may be combined together in any proportions or with other papermaking .material according to the quality of paper which it is required to produce.

In cases where the pithy or mucilaginous substance has been in part removed from megass or the like canes by a process prior to the treatment of the cane for the production of half-stuff, paper pulp or paper the remaining fibrous material may equally well be treated by the present process.

What I claim as my invention and desire to secure by Letters Patent is 1. A process for the treatment of megass, or like canes, for the production of papermakers half-stuff, paper pulp or paper, which consists in treating the previously crushed raw material by boiling 'or cooking it with a solution containing lime only, mellowing it, removing therefrom the pithy and mucilaginous substance together with other impurities by washing, and subsequently stance together with other impurities there-' from, by washing, and finally disintegrating V q the treated material.

3. A process for the treatment of megass, or likef'canes, for the production of paper makers" half-stuif, which consists in treating previously crushed raw material by boiling or cooking it with a solution containing lime only, mellowing it, removing therefrom the pithy and mucilaginous substance together with other impurities by washing, and finally disintegrating the treated material.

4. A processfor the treatment of megass,

makers half-stuff, which'consists in treating the previously crushed raw material byboiling or cooking it with a solution containing lime only, mellowing it, washing the cooked material and removing the pithy and 'or like canes, for the production of paperimpurities, then removing the excess Wash- Water, and-finally disintegrating the resulting material.

In testimony whereof I have signed my 15 name-to this specification in the presence of two subscribing Witnesses.

WILLIAM ARTHUR RANKEN MICHAEL MORAE.

Witnesses:

L G. Evns, H. D. JAMEsoN. 

